Currently, most of the fine patterns of electronic circuits in semiconductors, displays, and other electronic products are produced by using photolithography techniques; however, there are limits on inexpensive production using photolithography techniques. Moreover, when attempting to manufacture electronic products having increased surface areas, keeping manufacturing costs down while using fabrication methods employing photolithography has been difficult.
In view of this current situation, employment of printing techniques in manufacturing electronic circuits, sensors, and other devices, these being known as “printed electronics,” is being investigated. Such methods are expected to reduce amounts of chemical substances used and have attracted attention as environmentally friendly manufacturing processes. Moreover, such methods have been partially applied in printing electrodes of membrane keyboards, automotive window glass heating wires, and RFID (Radio Frequency Identification) tag antennas, among others.
Control of base material (printed side) wettability is of critical importance in printed electronics. Control of wettability is achieved by controlling surface free energy, and various methods therefor have been proposed. Among these proposals, base materials having a surface free energy difference patterning have been proposed.
For example, PLT, 1 describes a technique in which an electromagnetic wave is irradiated through a photomask to obtain a patterned base material composed of at least two regions having different surface free energies. Furthermore, PLT. 2 describes a technique in which an acrylic resin based photosensitive material to which has been added a fluororesin or silicone resin based surface migration additive, is applied, dried, and photocured to form a layer having a low critical surface tension on a surface.
However, the base material of PLT. 1 is produced by a photolithography method, thereby complicating methods for preparing the base material, and the base material of PLT. 2 has surface irregularities, thereby making selective application through only applying ink to the surface difficult.
Furthermore, PLT. 3 describes a technique in which a surface is modified with radiation or generated ozone via a mask to form a pattern with a difference in surface free energy. Furthermore, PLT. 4 describes a technique in which a low surface free energy portion is formed by partial exposure via a transparency difference of a Fresnel lens; thereafter, an unexposed portion is exposed to light in water to form a high surface free energy portion. Then, ink is applied to the created pattern and, thereafter, excess ink is removed to form the pattern. Furthermore, PLT. 5 describes a technique in which a low surface free energy portion is formed by partial exposure via a transparency difference of a Fresnel lens; thereafter, an unexposed portion is exposed to light in water to form a high surface free energy portion.
However, although a surface free energy difference is formed in the base material of PLT. 3, the surface free energy difference is small. Consequently, when ink is applied to the surface, entirely selective application is impossible and only a film thickness difference in a coated film can be formed.
Furthermore, although a surface free energy difference is formed in the base material of PLT. 4, as in PLT. 3, selective application through simply applying ink on the surface is impossible, and processes are required for peeling the ink from a portion (low surface free energy portion) where ink deposition is undesired.
Furthermore, although a pattern is formed by transferring a functional ink layer to a surface free energy pattern, PLT. 5 includes processes requiring heat and pressure application at the time of transferring in addition to a process for peeling away excess material.